The present invention relates to a method for creating restoration log files in a restoration log in a data system that includes software and hardware resources and a data base containing software representations of the resources, said resource representations containing data in associated attributes, and being able to be exposed to operations from a process associated with the data system or from an operations system for the data system. By a restoration log file is here meant something that shall reflect a resource representation updating performed from the process or from the operations system.
All computer systems associated with a process interact with the process as well as with operators and/or other operations systems. Examples of such systems are digital telecommunication switches, supervising systems for power distribution, and different types of manufacturing support systems. All these types of systems have a software representation of resources in the process. Such a resource representation can e.g. consist of a resource object in an object oriented system. The resource representation can be affected by an updating request from the process to the system. It can also be affected by an updating request from the operator and/or other systems. Later on the software representation can be affected due to an updating request from the process as well as from the operator.
In a telecommunication system subscribers are regarded as part of the process and their invoking of services is regarded as updating requests from the process to the switch. Services created from an operations support central are regarded as updating requests from another system/operator.
Common principles for system backup are that instant copies of all resource representations in a system are created with determined intervals, said instant copies being intended to be used for reloading in case of a system crash. Thereafter a restoration log is created with all updating commands from the operations system to the system. Normally, the restoration log contains no updatings originating from the process. In certain rare cases the initiator of an updating must create a restoration log record reflecting updating of the resource representation.
If the system does not support logging from a process one disadvantage of this principle is that certain or all updatings from the process are missing or erroneous depending on how well the initiators of the updating requests have followed the rule to create a restoration log record. The agreement between the restoration log and real updatings of the resource representations depend on a correct design by the initiator. Lack of correctness may turn out to be not visible until the restoration log shall be used for restoration of the system after a crash.
Another disadvantage is that the restoration log used for restoring will contain all updating requests from the operations system although only certain of these can be of value for a restoration.
Obviously it is therefore a great risk that a restoration can result in non-agreement between resource representations and the resources in the process.
EP 516,900 describes data backup and restoration in a data process system. The object is to eliminate the disadvantage of a great and unmanageable restoration log. A backup copy is taken of at least a part of stored data when this part is available for updating. Restoration of the data base is performed by introducing the backup copy and applying updatings in the log records done after a restoration.
U.S. Pat. No. 4,648,031 relates to restart of a data system after an interruption by means of resource managers including a restoration log.
U.S. Pat. No. 4,868,744 describes a method for restarting a fault tolerant operation in a data base system without charging the system log. According to the method only a minimum amount of information is logged. All transaction oriented changes are written to the log for supporting a restoration in case of an interruption.
U.S. Pat. No. 4,945,474 discloses system restart while using a restoration log and describes restoration in a plurality of steps.
U.S. Pat. No. 5,155,678 relates to data availability in restartable data base systems. A method is presented for switch over between a backup processor and an active processor after supervising of the log records of the active processor. When the active processor fails the backup processor performs the necessary restoration process.
U.S. Pat. No. 5,280,611 describes restoration of a data base after an error while using a log.
U.S. Pat. No. 5,287,501 relates to multiple level transaction restoration in a data base system. By operation logging the data base can manage plurality level restoration with very few restrictions with regard to the timing of updatings and log record.